Method of packaging flexible plastic bags

ABSTRACT

PORTION DEVELOPS THE INNER CONVOLUTION OF SAID REELED BAG, AND WHICH FURTHER INCLUDES REDUCING THE AIR PRESSURE IN SAID PASSAGES BELOW ATMOSPHERIC AT THE BEGINNING OF SAID REELING AND THEREAFTER JUST PRIOR TO SAID TRANSVERSE MOVING INCREASING THE AIR PRESSURE IN SAID PASSAGES TO ABOVE ATMOSPHERIC.   1. A METHOD OF PACKAGING FLEXIBLE PLASTIC BAGS COMPRISING THE STEPS OF SEQUENTIALLY ADVANCING BAGS ALONG A PREDETERMINED PATH, REELING EACH BAG UPON ITSELF ABOUT A MANDREL DISPOSED GENERALLY TANGENT TO SAID PATH, GRIPPING AN EDGE PORTION OF THE REELED BAG AND MOVING THE SAME TRANSVERSE TO SAID PATH TO CLEAR SAID PATH AND THEREAFTER RELEASING THE GRIP THEREON, AND TAMPING SAID REELED BAG INTO A CASE BY MOVEMENT PARALLEL TO SAID PATH, SAID MANDREL HAVING AIR PASSAGES CONFRONTING THE LEADING EDGE PORTION OF THE BAG AND WHICH

tates Patent Spencer METHOD OF PACKAGING FLEXIBLE PLASTIC BAGS Inventor:Harvey J. Spencer, Green Bay, Wis.

Assignee: Paper Converting Machine Company, Green Bay, Wis.

Filed: Apr. 24, 1972 Appl. No.: 246,554

[1.8. CI. 53/21 FW, 53/118 Int. Cl B65b 63/04 Field of Search 53/21 FW,118, 119

References Cited UNITED STATES PATENTS 2/1959 Goodwin 53/119 X 7/1930Baldenhofer 53/ll8 X Primary Examiner-Travis S. McGehee Attorney, Agent,or Firm-Dawson, Tilton, Fallon &

Lungmus 5 7] ABSTRACT A method for packaging flexible plastic bags ofsubstantial size (such as refuse bags for leaves) wherein the bags areadvanced sequentially along a predetermined path and successively reeledon themselves about a pair of rotating mandrels, the mandrels beingoscillated together so as to alternately come into positions ofapproximate tangency to the predetermined path and alternately, aposition where the reeled bag is stripped, and, after stripping in adirection transverse to the predetermined path, the stripped bag istamped into a carton whereby each bag is essentially flat foldedindependently of the other bags in the carton.

11 Claims, 15 Drawing Figures PATENIEQ 081 2 219M SHHEN 6 METHOD OFPACKAGING FLEXIBLE PLASTIC BAGS BACKGROUND AND SUMMARY OF INVENTIONWhere refuse bags of substantial size are prepared for marketing, aproblem has arisen in packaging. A simple expedient employed previouslyhas been to fold the bags (usually six to 12) simultaneously so that thebags are interfolded. Although this is simple from the standpoint ofproduction, it has caused considerable trouble in use the user oftenvirtually destroying the package in order to get a single bag out freeof the others. On the other hand, it has been found expensive and timeconsuming to fold the bags independently and insert them into the retailcarton.

According to the instant invention, these twin difficulties are avoidedand this through the use of a high speed mechanism which rapidly windsor reels each bag on itself in after which the bag is translated, i.e.,stripped from the winding mandrel into a position over the receivingcarton. Thereafter the bag in its reeled condition is tamped into thereceiving carton and incident to this becomes flattened so that it hasthe desired configuration of being flat folded.

DETAILED DESCRIPTION OF THE INVENTION The invention is depicted inconjunction with an illustrative embodiment including apparatus, for thepractice thereof and in which:

FIG. 1 is a fragmentary perspective view of apparatus employed for thepractice of the invention;

FIG. 2 is a schematic view of the apparatus of FIG. 1 in a firstoperational condition;

FIG. 3 is a side elevational view, also essentially schematic, of theconfiguration of apparatus of FIG. 2;

P15. 4 and 5 are schematic views corresponding essentially to thedepictions in FIGS. 2 and 3 but wherein the apparatus is in a subsequentoperational state;

FIGS. 67 and FIGS. 8-9 are views corresponding respectively to FIGS. 2-3and 4-5 but showing the apparatus in third and fourth operationalstates;

FIG. 10 is a fragmentary plan view of the apparatus and which isparticularly concerned with the drive for the mandrels;

FIG. 11 is a side elevational view of the air system componentsassociated with the mandrels for facilitating reeling and stripping;

FIGS. 12 and 13 are fragmentary sectional views taken along the lines12-12 and l313 respectively in FIG. 11;

FIG. 14 is an end elevational view of the inventive apparatus and showsparticularly the means for actuating the devices employed for strippingand tamping; and

FIG. 15 is a plural graph chart showing the timed relationship of thevarious steps employed in the practice of the invention according to thepreferred form shown herein.

In the illustration given and with particular reference to FIG. 1, thenumeral designates generally a conveyor which is seen to support bags Band B which are located in longitudinally spaced apart relation as by agap therebetween. The development of this gap is described in greaterdetail hereinafter. Essentially it stems from the fact that the bags arereeled faster than they are advanced on the conveyor 20.

Advantageously, the conveyor 20 is of the vacuum type consisting of ascreen or foraminous belt sliding over an apertured suction'box.Upstream of the portion of the conveyor 20 shown in FIG. 1 are locatedconventional folding and cutoff devices (not shown).

In FIG. 1, only one mandrel 21 is shown to facilitate 5 quickunderstanding of the operation of the inventive method. It will beappreciated that in the preferred form of the invention as depicted inthe remaining figures of the drawing, a pair of mandrels are provided.

Mounted in juxtaposition to the mandrel 21 is a brush 10 22 which isadapted to hold down the trailing end of a bag B being reeled on themandrel 21. After the reeling has been completed, a picker mechanism 23advances coaxially relative to the mandrel 21 (advancing to the left inFIG. 1). A gripper 24 is provided on the adjacent 1 end of the picker 23which is adjacent the mandrel 21 and grips an edge portion of the bag Bafter the same has been completely reeled. Retraction of the pickermechanism 23 positions the reeled bag under a tamper 25 whichreciprocates in a direction parallel to the pre- 20 determined path ofthe conveyor 20 and tamps the reeled bag into a carton 26 e and incidentthereto flattens the same so as to develop the desired flat foldedconfiguration of bag.

Turning now to FIGS. 2-9, it will be seen that a second mandrel 27 isdepicted schematically and that both the mandrels 21 and 27 arerotatably mounted on a mandrel pivot arm 28 which is rockably mounted ona cross shaft 29 (also depicted schematically but which will bedescribed hereinafter with reference to FIG. 10). In FIG. 2 it is to benoted that the bag B has been completely reeled whereas in FIG. 1 thebag B is still in the process of being wound.

In FIGS. 4 and 5, a subsequent stage of operation is shown where the bagB previously wound on the mandrel 21 has been stripped therefrom and isready for tamping into the carton C. Meanwhile the bag B has been almostwound on the mandrel 27. The mandrels are shown in the process of beingindexed, i.e., oscillated to move the mandrel 21 upwardly into tangency(as at 21a in FIG. 4) with the conveyor 20. The mandrel 27 is also shownin a position intermediate the ends of its oscillatory path no longerbeing approximately tangent to the conveyor 20 as it was in FIG. 2 butnot quite in the stripping position as it is in FIG. 6.

In FIGS. 6 and 7, the mandrel positions are the reverse of that seen inFIGS. 2 and 3 while in FIGS. 8 and 9, the positions are reversed fromthat of FIGS. 4 and 5. Thus, a given cycle of operation includes reelingof one mandrel while stripping the second, moving the wound mandrel tothe stripping position while moving the stripped mandrel to the windingposition, reeling the second mandrel while stripping the first, andfinally moving the second to the stripping position while moving thefirst back to the winding position. The stripping positions for bothmandrels is the same (compare FIGS. 2 and 6) while the winding positionsare different athough in both cases there is approximate tengency to theconveyor 20 (again compare FIGS. 2 and 6).

Reference is now made to FIG. 10 for additional details of preferredmechanism for achieving the inventive method. In FIG. 10, pulleys 30 and31 are mounted on the mandrels 21 and 27 respectively and through drives32 and 33, respectively, derive rotational power from pulleys 34 and 35.The pulleys 34 and 35 are fixed to the cross shaft 29 and are coupled,respectively to gears 36 and 37. It will be appreciated that input tothe gears 36 and 37 can be achieved from a variety of indexingmechanisms and for that purpose one such is schematically represented bythe numeral 38, this, along with the cross shaft 29 being operativelyassociated with the frame generally designated 39 (see FIG. 1).

Still referring to FIG. 10, it will be seen that the unsupported orstripping end of the mandrels is equipped with an end portion 40 havinga cutout 40a which provides an unsupported portion of the reeled bag forgripping by the gripper 24. Arcuate slots in the end portion 40 permitrotary adjustment of the end portion 40 (via bolts 40b) so that thecutout 40a is properly aligned with the gripper 24.

It will also be noted that the mandrels 21 and 27 are equipped with airpassages or apertures 42 which are adapted to be in confronting relationwith the innermost convolution or wrap of a bag being reeled. The airpassages 42 communicate with an air manifold 43, the purpose of which isto selectively apply vacuum or pressure to a given mandrel. At thebeginning of a reeling cycle, the air passages 42 are subjected tovacuum, i.e., the air pressure therein is reduced to below atmosphericso as to cause the bag to be readily transferred from the conveyor 20 tothe mandrel in the winding position, viz., the position of the mandrel27 in FIG. 2. Toward the end of the reeling cycle, the mandrel has theair passages thereof subjected to air pressure, i.e., to a pressuregreater than atmospheric so as to facilitate the stripping of the reeledbag axially off of the mandrel. The pressure air flowing out of thepassages 42, in effect, provides a lubricant facilitating the strippingmovement.

For the purpose of selectively applying vacuum and pressure to mandrels,the mandrel pivot arm 28 is equipped with a banana-shaped fitting 44(see FIG. 11) which is coupled to the two air manifolds 43 and 43aassociated with the mandrels 21 and 27. The fitting 44 is in sliding,generally sealed relationship with a stationary manifold plate 45resiliently attached to the frame 39 (see FIG. 13). The plate 45 hasbores 4648 provided therein. The bores 46 and 48 are coupled to a sourceof vacuum (not shown) while the intermediate bore 47 is coupled to asource of compressed air (also not shown). Thus, as the mandrelsoscillate over an arcuate path, one mandrel is coupled to a vacuum (whenthat particular mandrel is in the reeling position) while the othermandrel is coupled to a source of compressed air while that mandrel isin the stripping position. It will be noted that both mandrels assumethe same position for stripping, the stripping position beingintermediate the ends of the arcuate path which brings the respectivemandrels into approximate tangency with the conveyor 20. For the purposeof communicating-the pressure or vacuum from the stationary manifoldplate 45, the fitting 44 is equipped with bores 49 and 50 as can be seenbest in FIGS. 12 and 13. As seen in FIGS. 11-13, the mandrel 21 is inthe stripping position, i.e., away from the conveyor 20. Its associatedbore 49 in the fitting 44 is aligned with the pressure passage 47. Themandrel 27 is in the reeling position, i.e., generally tangent to theconveyor 20. Its associated bore-50 in the fitting 44 is aligned withthe vacuum passage 46. When the mandrel 21 is in the reeling position,the bore 49 is aligned with the vacuum passage 48 and the bore 50associated with the mandrel 27 is aligned with the pressure package 47.

Before going on with the remainder of the description of the preferredform of mechanism for practicing the invention, reference is made toFIG. 15 which includes a plurality of graphs setting forth the timedrelationship of the various steps and apparatus employed. The uppermostgraph is seen to be designated mandrel No. 1 winding velocity and has todo with the surface speed of the mandrel 21. The third curve from thetop shows the pattern of velocity or surface speed changes in the othermandrel 27 (designated No. 2 mandrel).

Referring to the curve for mandrel No. 1, it will be seen that at thestart of a given cycle, the velocity increases from zero to a maximumwhich occurs about one-eight to one-quarter through a total cycle. Thegraphs in FIG. 15 have been set up so that one cycle includes (1) thereeling of one bag, (2) the movement of the mandrel on which that baghas been reeled to the stripping position, (3) the dwell time in thestripping position and (4) the return of the mandrel to a position forreeling a third bag it being appreciated that the second bag is beingreeled on the second mandrel during the stripping of the first bag fromthe first mentioned mandrel.

Thus, it will be seen that the third curve shows no rotational velocityof the mandrel No. 2 during the time mandrel No. 1 is in the windingmode. Referring again to the topmost curve in FIG. 15, it will be seenthat there is a constant velocity or surface speed of the mandrel No. 1for a substantial portion of the cycle. This speed is set to be slightlyfaster than the linear speed of the conveyor 20 so that the outerconvolutions of the reeled bag are relatively tight. However, the speedat pickup is somewhat slower than the linear speed of the conveyor 20.This insures that the innermost convolution or the first wrap around themandrel will be relatively loose so as to insure easy removability.Reeling of the bag generally completes as the mandrel No. 1 reaches thedeceleration portion of its rotation approximately the third quarter ofthe cycle.

The gap G is developed between the bags B and B on the vacuum belt ofthe conveyor 20 because the mandrels wind at a rate greater than therate the bags are being carried on the conveyor 20. The indexing device38 driving the mandrels provides an acceleration period, a constantvelocity period, a deceleration period, and a non-rotational period.More particularly, the bags are picked up by the vacuum in the reelingmandrel during the acceleration period, but at a point where thevelocity of the surface of the mandrel is below the velocity of the bagon the conveyor 20. This allows each bag to be picked up without tensionon the bag. Pickup occurs after the time vacuum is applied but beforethe mandrel reaches its constant velocity mode. After each bag has madeapproximately one wrap or convolution and is firmly gripped by themandrel, the velocity of the surface of the mandrel continues toincrease to a value greater than the velocity of the vacuum beltconveyor 20 and the bag is caused to slip on the conveyor 20 to pull thebag being wound ahead of the next bag in the stream. Since the constantvelocity period of rotation of the mandrel is at a greater velocity thanthe vacuum belt velocity, the bags are wound under tension for all butthe first revolution of the wind. The diameter-of the mandrel, thenumber of convolutions of wind and the pickup point are all designed toposition the tail of the bag on top of the mandrel under the wiper brush22 when the mandrel stops rotating in the strip position.

Referring now to the second curve (counting from the top of FIG. theposition of both the mandrels No. 1 and 2 are depicted. The variouspositions are labeled and it will be seen that during the firstapproximately 120 of a given 720 cycle, the mandrel No. 1 is moving tothe pickup position. Thereafter for about 240, the mandrel No. 1 is in adwell position for the winding or reeling of a bag. The next approximate120 sees the mandrel being indexed to the strip or removal position,after which there is another substantial dwell period of about 240 forthe actual stripping of the reeled bag from the mandrel.

Also indicated on the first and third curves are the conditions ofpressure or vacuum on the two mandrels. The vacuum condition existsrelative to the apertures 42 during the entire winding or reelingportion of the cycle for so long as the mandrel 21 is in the windposition because at that time the bore 49 is aligned with the passage48. After the mandrel 21 has the bag B reeled upon it and has beenindexed almost to the strip position, the bore 49 in the fitting 44 isaligned with the intermediate bore 47 so as to deliver compressed air tothe passages 42. Thus, for a short period before and after reeling, themandrel is subjected to vacuum while the mandrel is subjected to airpressure for a period shortly before and during the stripping.

Turning now to FIG. 14, the numeral 51 generally designates the actuatorfor the picker mechanism 23. It will be appreciated that the pickermechanism is essentially a reciprocating mechanism which moves thegripper 24 into and out of engagement of a cantilevered edge portion ofthe reeled bag. For this purpose, the picker is slidably received withina guide 52.

The numeral 53 designates the movable jaw of the gripper 24 while thenumeral 54 designates the stationary jaw. The movable jaw 53 is coupledby means of a cable 55 to a cam follower arm 56 which carries a camfollower 57. The cam follower arm is seen to be mounted on the pickermechanism 23 and moves therewith. Normally, the movable jaw 53 is urgedinto gripping contact with the stationary jaw 54 by means of a tensionspring 58 extending between the jaw 53 and a spaced portion on thepicker mechanism 23. However, as the picker mechanism advances axiallytoward the mandrel in the stripping position, the cam follower 57 comesinto contact with a rotating cam 59. The rotating cam 59 is programmedso that just as the gripper 24 is about to engage the edge of the reeledbag, the cam follower arm 55 is rocked so as to temporarily open thejaws 53-54. Thereafter, the jaws snap shut about a portion of the reeledbag and remain in that position until the picker mechanism 23 isvirtually completely retracted, i.e., until the cam follower 57 engagesa fixed cam surface 60. This results in opening the jaws 53-4 so thatthe tamper 25 can perform its function in separating now stripped reeledbag from the gripper 24 and into the carton 26. v

The timed sequence of the picker mechanism 23 and gripper 24 are seen onthe fourth and fifth curves (counting from the top) of FIG. 15. It willbe appreciated that each of these functions is performed twice eachcycle of 720 as designated. Thus, as the mandrel No. 1 has been indexedto the stripping position (reaching that at about 480) the pickermechanism 23 is almost adjacent the end of the mandrel No. 1. On thefifth curve relating to the gripper 24 and in the portion between 450and 540, two sinusoidal curves are seen which are placed in proper timedrelation to the other curves. The first curve shows the opening of thegripper while the second curve shows the closing of the gripper on thebag reeled on mandrel No. l.

The last curve on FIG. 15 relates to the tamper 25. The apparatuspreferred for the achievement of the operation of the tamper is alsoseen on FIG. 14 where the numeral 61 generally designates the tamperguide and the numeral 62 designates the tamper actuator, i.e., themechanism which controls the reciprocation of the tamper in accordancewith the timed program depicted on FIG. 15. In FIG. 15, it will be seenthat the tamper goes through two complete reciprocations for each cycle.In the illustration given, the times contemplated by the graphs in FIG.15 which are generally to scale, are of the order of 0.8 seconds for acomplete cycle of 720.

In the operation of the device and with respect to FIGS. 2-9, the sideview of FIG. 2 shows the vacuum belt of the conveyor 20 and the lowerpulley 63 associated therewith and with the mandrel pivot arm 28 and itspivot point 29 (actually the axis of the cross shaft 29). This is seento the left. The mandrel 21 has completed the winding of the bag B andthe mandrel 27 has just picked up the bag B. The front view in FIG. 3shows the picker 23 gripping the bag via the gripper 24 with the tamper25 in a raised position. During this period of operation, the vacuum ison for the mandrel 27 and the air pressure is on for the mandrel 21. Thewiper 22 is engaging the top of bag B on mandrel 21 and holding the tailof this bag in place on the mandrel. The bag carton 26 is shown belowthe tamper in FIG. 3.

In'FIG. 4, the showing is slightly later in the cycle from that of FIG.2 the bag having been removed from the mandrel 21 and the bag B beingpartially wound on the mandrel 27. The mandrel pivot arm 28 is in theprocess of being pivoted upward to put the mandrel 27 in position topick up a subsequent bag B from the vacuum belt conveyor 20. The frontview as seen in FIG. 5 shows the picker 23 moved all the way to theright and having released the bag B previously wound on the mandrel 21against a set of stripper bars 64. FIG. 5 also shows the tamper in twopositions. The solid line position shown is just after the bag B hasbeen released by the gripper 24 of the picker 23. The dotted lineposition of the tamper 25 is as it approaches the bottom end of itsstroke. During this period of operation there is no vacuum or airpressure on the mandrel 21, but there is vacuum on the mandrel 27. Thewiper 22 is seen to be in a retracted position 22"so as to ptrmit theindexing or oscillation of the mandrel 21. For this purpose the wiper 22is mounted on a retractable bracket65 (see FIG. 1) which is operablyassociated with the indexing device 38.

In FIG. 6 the side view is generally the same as in FIG. 2 except thatthe mandrels are in the reverse position. In the front view FIG. 7, thepicker 23 is shown before the bag B is gripped instead of just aftergripping as is the case in FIG. 3.

In FIG. 8, the side view is generally the same as FIG. 4 except thepositions of the mandrels are reversed and the same applied to theshowing in FIG. 4 as contrasted to that of FIG. 5.

I claim:

l. A method of packaging flexible plastic bags comprising the steps ofsequentially advancing bags along a predetermined path, reeling each bagupon itself about a mandrel disposed generally tangent to said path,gripping an edge portion of the reeled bag and moving the sametransverse to said path to clear said path and thereafter releasing thegrip thereon, and tampingsaid reeled bag into a case by movementparallel to said path, said mandrel having air passages confronting theleading edge portion of the bag and which portion develops the innerconvolution of said reeled bag, and which further includes reducing theair pressure in said passages below atmospheric at the beginning of saidreeling and thereafter just prior to said transverse moving increasingthe air pressure in said passages to above atmospheric.

2. A method of packaging flexible plastic bags comprising the steps ofsequentially advancing bags along a predetermined path, reeling each bagupon itself about a mandrel disposed generally tangent to said path,rotating said mandrel at a surface speed at the beginning of saidreeling lower than the speed of the bag in said path to provide a loosewrap on the mandrel and thereafter before reeling is complete increasingthe surface speed of the mandrel to greater than that of the bag in saidpath, gripping an edge portion of the reeled bag and moving the sametransverse to said path to clear said path and thereafter releasing thegrip thereon, and tamping said reeled bag into a case by movementparallel to said path.

3. The method of claim 2 in which the increase of mandrel surface speedoccurs after approximately one convolution of the bag to be reeled hasbeen achieved.

4. The method of claim 2 in which the increased mandrel surface speed ismaintained substantially throughout the remainder of the reeling of thebag.

5. A method of packaging flexible plastic bags comprising the steps ofsequentially advancing bags along a predetermined path, reeling each bagupon itself about a mandrel disposed generally tangent to said path,said reeling being achieved on a pair of mandrels and which furtherincludes simultaneously oscillating said mandrels over an arcuate pathto serially position one mandrel approximately tangent to saidpredetermined path and the other mandrel spaced from said predeterminedpath and in position for reeled bag transverse movement, gripping anedge portion of the reeled bag and moving the same transverse to saidpath to clear said path and thereafter releasing the grip thereon, andtamping said reeled bag into a case by movement parallel to said path, agiven bag being reeled while a preceding reeled bag is being movedtransversely and being tamped.

6. The method of claim 5 in which said gripping occurs when each mandrelis at the end of said arcuate path corresponding to said position forreeled bag transverse movement, said gripping occuring at about thecommencement of the reeling of the succeeding bag on the mandrel in saidapproximately tangent position.

7. The method of claim 6 in which the mandrel in said approximatelytangent position is being rotationally accelerated during the grippingof the reeled bag on the mandrel in the position for reeled bagtransverse movement.

8. The method of claim 6 in which said reeled bag transverse movement iscompleted at about the completion of reeling of a succeeding bag and inwhich said tamping occurs during arcuate path movement of a mandrel intoapproximate tangency to said predetermined path.

9. A method for the rapid packaging of refuse bags comprising advancingbags sequentially along a predetermined path while simultaneouslyindexing a pair of spaced apart mandrels into and out of approximatetangency to said path whereby when one mandrel is approximately tangentthe other mandrel is spaced from said path, temporarily stopping saidindexing to cause said mandrels to dwell in respective positions andduring said dwell reeling a bag on the approximately tangent mandrelwhile stripping a previously reeled bag from the other mandrel in thedirection transverse to said predetermined path and generally flatteningsaid stripped bag into a case by movement in a direction parallel to butspaced from said path and during the indexing of said mandrels.

10. The method of claim 9'in which the reeling is achieved by a surfacespeed of said mandrels greater than the speed of advance of said bags insaid path to provide a gap between the trailing edge of one bag and theleading edge of the succeeding bag.

11. The method of claim 9 in which said mandrels are equipped with airpassages selectively communicated with air pressure and vacuum andwherein vacuum is applied to said mandrel during reeling and airpressure is applied during stripping.

